(a) Technical Field
The present disclosure relates to a passive hood hinge system for a vehicle, and more particularly, to a passive hood hinge system for a vehicle capable that reduces injuries to a pedestrian by compressing a hood upon collision into the hood to relieve an impact applied to the pedestrian.
(b) Background Art
Generally, a front portion of a vehicle is provided with an engine compartment which is accessible via a hood. The hood of the vehicle provides access to the engine compartment and provides a shield of the engine compartment to block engine noise. The hood has both left and right sides of a rear end portion coupled with a vehicle body around the engine compartment by a hood hinge assembly to provide access to the engine compartment while being rotated based on the hood hinge assembly.
The existing hood hinge assembly of the related art maintains the rigid position of the hood and thus when a vehicle impacts a pedestrian, the pedestrian's body may be wounded by the impact of the vehicle. Accordingly, various pedestrian protection technologies that comply with pedestrian protection regulations and improvement in vehicle marketability have been developed. For example, an active hood system secures a space between the hood and the engine compartment to absorb impact energy.
The active hood system of the related art is a system that instantly disengages the hood upon the impact to protect the pedestrian and reduces injuries to the pedestrian. For example, the rear end portion (e.g., hood hinge assembly) of the hood is disengaged and elevated to reduce an injury value while mitigating the pedestrian impact. In the existing active hood system, when a crash detecting sensor senses the pedestrian crash, a controller operates an actuator in response to a sensor signal to disengage and elevate the rear end portion of the hood, thereby creating a buffer space between the hood and the engine compartment.
However, the existing active hood system may be problematic due to the non-operation and malfunction of the crash detecting sensor. Further, the current system may excessively increase the cost and weight of the vehicle due to the complex configuration of the controller, the crash detecting sensor, the actuator, or the like.
Conversely, unlike the active hood system that disengages and elevates the hood upward upon the pedestrian crash, a passive hood technology reduces the injury value of the pedestrian by disengaging and vertically translating the hood from an initial position to a second position that is vertical lower than the initial position has been developed. For example, the hood hinge system to dampen the hinge assembly by a spring during the crash occurrence has been proposed. However, the passive hood hinge system has unstable lock performance due to the absence of an impact recognizing component. Accordingly, the system may malfunction and may increase the size, costs, and weight due to the application of the spring.
Further, a method for absorbing energy through a spring does not provide control over a spring constant. In particular to increase an impact absorption amount and secure sufficient energy absorption performance, a length of the spring is required to be extended. As a result, the weight and costs may be increased due to the increase in the size of an impact absorbing component including the spring and the injury value may be increased due to the rebound of the spring. Further, when the spring structure passes through an electro-deposition bath for electro deposition coating, the spring has a functional problem due to the stagnation and deposition of an electro deposition filtrates. For example, the spring is separately assembled in a trim assembling line, etc., thereby limiting vehicle mass production process.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.